Earth's Crust in Motion



Vocabulary


Earthquake: Shaking and trembling that results from the movement of rock beneath Earth's surface.
Stress: A force that acts on rock to change its shape or volume.
Shearing: Stress that pushes a mass of rock in two opposite directions.
tension: a stress force that pulls on the crust stretching rock so that it becomes thinner in the middle.
Compression: A stress force that squeezes rock until it folds or breaks.
Deformation: Any change in the volume or shape of Earth's crust.
Fault: A break in Earth's crust where slabs of crust slip past each other.
Strike-slip fault: When the rocks on either of the fault slip past each other sideways with little up or down motion.
Normal Fault: When the fault is at an angle, so one block lies above the fault while the other block lies below the fault.
Hanging Wall: The half of the fault that lies above.
Foot Wall: The half of the fault that lies below.
Fault-Block Mountain: When normal faults uplift a block of rock.
Folds: Bends in rock that form when compression shortens and thickens part of Earth's crust.
Anticline: A fold of rock that bends upward into an arch.
Syncline: A fold of rock that bends down in the middle to form a bowl.
Plateau: Large are of flat land elivated high above sea level.


Outline


Stress in the Crust


Types of Stress

    • Shearing, tension, and compression work over millions of years to change the shape and volume of rock.

Kinds of Faults

    • Faults usually accur along plate boundaries, where the forces of plate motion compress, pull, or shear the crust so much that the crust breaks.
  • Strike-Slip Faults
  • Normal Faults
  • Reverse Faults

Friction Along Faults


Mountain Building

    • Over millions of years, fault movement can change a flat plain into a towering mountain range.
  • Mountains Formed by Faulting
  • Mountains Formed by Folding
  • Anticlines and Synclines
  • Plateaus

Diagrams


CMDV2.1.jpg
Deformation of rocks